Dense kelp covered reefs before the heatwave. Reef in Kalbarri before (left) and after (right) the 2011 Ningaloo Nino. Projections suggest the southwest could be in a permanent state of marine heatwave within 20-40 years, compared to the second half of the 20th century. Some of these fisheries have not recovered 10 years later, while others are only now reopening. Recreational and commercial fisheries were forced to close to protect ailing stocks. Little penguins starved to death because their usual food sources were no longer there. Coral bleached in the state’s north, fish died en masse, 34% of seagrass died in Shark Bay, and kelp forests along 100km of WA’s coast were wiped out.įollowing the heatwave came sudden distribution changes for species like sharks, turtles, and many reef fish. Over eight weeks, ocean temperatures soared by more than 5℃ above the long-term maximum. In 2011, a combination of weak winds, water-absorbing the local heat from the air, and an unusually strong flow of the warm Leeuwin Current led to the infamous marine heatwave known as Ningaloo Nino. Marine heatwaves are now striking alongside this long-term warming trend. Temperature anomalies over land and ocean in March 2011. They can’t survive in the deep sea and are at risk of going extinct.

Once cool-water species reach the southern coast, there’s nowhere colder to go. Warm-water species move in and cool-water species flee to escape the heat.

Many species of seaweeds, seagrasses, invertebrates, reef fish, seabirds, and mammals live nowhere else on the planet.Īs the waters warm, species move south. The waters off the southwest are part of the Great Southern Reef, a temperate marine biodiversity hotspot. Ocean temperatures off Perth have risen by an average of 0.1-0.3℃ per decade, and are now almost 1℃ warmer than 40 years ago. The seas around the southwest are another climate change hotspot, warming faster than 90% of the global ocean since the middle of last century. Hotter seas, destructive marine heatwaves Increased heating and drying will also likely threaten Margaret River’s famed wine region, although the state’s northern wine regions will be the first at risk. Aided by innovation and better varieties, wheat yields in the southwest have actually increased since the 1970s, despite the drop in rainfall.īut how long can farmers stay ahead of the drying? If global emissions aren’t drastically reduced, droughts in the region will keep getting worse. Long term, the flowering rates of banksias have declined by 50%, which threatens their survival as well as the honey industry.įor agriculture, the picture is mixed.

What does that look like on the ground? Think beetle swarms taking advantage of forest dieback, a sudden die off of endangered Carnaby’s Black Cockatoos, and the deaths of one in five shrubs and trees. This was particularly dire in 2010/2011, when all ecosystems in the southwest suffered from a deadly drought and heatwave combination. The story on land is also alarming, with intensifying heatwaves and chronic drought. Smooth Marron moving as a group in a reservoir. To protect remaining freshwater species we must develop perennial water refuges in places such as farm dams. As river flow falls to a trickle, fish can no longer migrate to spawn, and it’s only a short march from there to extinction. Most native freshwater fish in the southwest are now officially considered “threatened”. The drying also makes it very hard for animals and birds to find water. The loss of water has even killed off common river invertebrates, such as the endemic Western Darner dragonfly, with most now found only in the last few streams that flow year-round. For example, the number of invertebrate species in 17 lakes in WA’s wheatbelt fell from over 300 to just over 100 between 19. It means many rivers and lakes now dry out through summer and autumn, causing major problems for freshwater biodiversity. That might not sound dangerous, but the drop means river flows have already fallen by an alarming 70%. Drying threatens wildlife, wine and wheatĪnnual rainfall in the southwest has fallen by a fifth since 1970. As climate change worsens, these winds are projected to get more intense, bringing still more heat. The southwest already has very hot days in summer, thanks to heat brought from the desert’s easterly winds. Almost all climate models project a further drop in winter rainfall of up to 30% across most of the southwest by 2100, under a high emissions scenario. Australian Bureau of Meteorology.Īnd remarkably, a 1℃ increase in the average global temperature over the last century has already more than doubled the days over 40℃ in Perth.Ĭumulative number of days over 40° at Perth Airport over 30-year periods between 1910-1939 (historic) and 1989-2018 (current).

Heat marine wildlife masse